The DirectWrite font backend is an optional backend which is planned to take over as the default on Windows. In order to do this, though, a few gaps need to be filled in order for it to pass all autotests. The following things are covered by this: 1. Bitmap fonts are unsupported in DirectWrite. We enumerate these using GDI and fall back to the GDI font engine when loading them. As part of this, we introduce a new handle type for fonts on Windows which can represent both the DirectWrite and GDI engines. 2. "Legacy font names" where sub-family is embedded in the family name is now enumerated together with the typographic font name. 3. The DirectWrite font engine was not loading kerning pairs from the font, like the other engines (omission which was detected by the test) 4. Turning off antialiasing does not work with DirectWrite, so we fall back to GDI for this. 5. Loading supported writing systems from application fonts was not supported. Task-number: QTBUG-119420 Change-Id: Icf6c351afb0d7487b2f4634199088d701a324aae Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>